Mark-recapture and satellite tracking in rehabilitated juvenile grey seals (Halichoerus grypus): dispersal and potential effects on wild populations

Published source details Vincent C., Ridoux V., Fedak M.A. & Hassani S. (2002) Mark-recapture and satellite tracking in rehabilitated juvenile grey seals (Halichoerus grypus): dispersal and potential effects on wild populations. Aquatic Mammals, 28, 121-130.
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This study is summarised as evidence for the following.

	Action	Category
	Rehabilitate and release injured, sick or weak marine and freshwater mammals Action Link

Rehabilitate and release injured, sick or weak marine and freshwater mammals

A study in 1989–1999 of multiple sites in the North Atlantic Ocean, off the coast of Brittany, France (Vincent et al. 2002) found that at least a quarter of stranded grey seal pups Halichoerus grypus that were rehabilitated and released back into the wild survived and were re-sighted alive. Twenty-five of 92 (27%) rehabilitated seal pups were re-sighted alive 1–49 times up to five years after release. Nineteen pups (21%) were re-sighted dead. Survival was not known for the other 48 pups, which were not seen again. Seventeen of the seals re-sighted alive settled at two grey seal haul-out sites close to release sites or along the coast. Eight seals dispersed across the English Channel. In 1989–1999, ninety-two seal pups (aged a few days to a few months old) were found stranded and underweight and taken to a rehabilitation facility. They were released at sea after one month of rehabilitation (in 1989–1990) or after they reached a weight of 40–45 kg (in 1991–1999). All 92 pups were marked with flipper tags. Some were additionally marked with coloured markings (40 pups) or head tags (28 seals) or were photographed for identification (25 seals) or satellite-tagged (four seals). Opportunistic observations were made of released seals both on shore and at sea (dates not reported). The four satellite-tagged seals were tracked for 14–80 days in June–September 1997.

(Summarised by: Anna Berthinussen)